DESCRIPTION (Investigator's Abstract) This proposal describes the Upstate New York Participating Center's resources, personnel and CRYO-ROP patient population for the purpose of participating in the two proposed Multicenter Studies of the long term follow-up of infants in the CRYO-ROP trial. The Upstate Center has 26 infants from the CRYO-ROP Randomized/Special Prethreshold Cohort, and 196 from the less than 1000g birth weight Natural History Cohort. The Multicenter CRYO Phase III Study's purpose is to examine the long- term structural and functional effects of cryotherapy as a treatment for severe retinopathy of prematurity (ROP). In the initial phase of the study, 291 infants of less than 1251g birth weight were randomized to receive cryotherapy to one eye. Follow-up at 3 and 12 months in Phase I and to date to 12 months in Phase II, indicates that cryotherapy significantly reduces the number of children with unfavorable ophthalmic structural outcomes and unfavorable resolution acuity. CRYO Phase 111 proposes to follow the randomized group and an additional small subgroup (n equals 67) of potentially high risk ROP patients (Special Prethreshold) from the Natural History study through age 10 years to determine whether the reduction in the benefit of cryotherapy seen between ages 12 and 42 months continues into mid-childhood. Evaluation of the effects of cryotherapy will be based on examination findings in the posterior pole of the eye and on assessment of visual acuity, as in Phase II. In addition, a more complete evaluation of visual function will be conducted at age 9 years through assessment of monocular contrast sensitivity, monocular color vision, and stereopsis. At 10 years Goldmann perimetry will also be assessed. The Multicenter study of the Natural History Cohort of infants weighing less than l000g at birth proposes to follow 760 infants in 5 centers to study their visual development in relation to ROP and the Randomized (cryotherapy) Cohort linked with the results of the same visual assessments that are proposed for the Randomized group. In addition, their developmental outcomes will be determined at 10 years to permit more precise cost effectiveness analyses over time. ROP is one of the major morbidities affecting the increasing number of extremely low birth weight survivors.